George eastman



learn STATES PATENT FFICE.

GEORGE EASTMAN, OF ROCHESTER, NEW YORK, ASSIGNOR, BY MESNE AS:

SIGNMEN'lfi-TQ THE EA S'lhlAN KODAK COMPANY,

OF SAME FLA-C MANUFACTURE osPHoToeRAP'mc FILM.

SPECIFICATION forming part of Letters Patent No. 584,862, dated J is 22,1897.

i Application filed February 15,1892.

1'0 all whom it may concern:

Be it known that I, GEORGE EASTMAN, of Rochester, in the county ofMonroe and State of New York, have invented certain neiv and 5 usefulImprovements in Photographic Film and Methodsof lilanufacturingthe Same;and

I do hereby deciarcthe following te b' such a full, clear,and exactdescription of the same as will enable one skilled in the art to prac-TO tice the invention. 7 p

In the manufacture and use of photographic film such is now ingeneraluse, consisting of a base or support of a nitrocellulose or similarcompound, provided with a sensitive r5 coating ofgelamndargentic"emulsion, a considerablc difficulty has manifesteditself and large quantities of film-have been rendered worthless byreason of the streaks ormarkings found in the sensitive coating upon de-20 velopment, caused by the sparks or electrical discharges producedwhen the him is rolled or unrolled in the roll-holders used forcarryingitin long lengths, and also oftentimes during its manufactureand subsequenttreat- 2 5 ment, as when out into'strips or wound on thespools. These discharges manifest themselves as sparks, which aresufficiently bright to fog the sensitive emulsion in lines resemblingdischarges of static electricity, as seen, o-for instance, in flashes oflightning or discharges from a static electrical machine. Of

course when thefilm is in this way practieally exposed duringmanufacture it is ren- 0 is therefore the object of my present inventionto obviate this difliculty and prevent the formation of these sparks ordischarges by rendering the iilmsupport non-electric, so

to say, by the addition to it of a suitable 1nate= 4 5 rial which willnot affect to any appreciable ex-' tout the quality of the support as, asupporte that is, will not render it too opaque for pho tographic usesbyprecipit-atin g any of thsub- Serial No 421,626. No specimens.)

or coloring it, nor. affect the sensitiveness of the emulsionv appliedto it.

After considerable experimenting I have discovered that ifa smallquantity of a me, tallic salt possessing the above characteristics andsoluble in the solvents of nitrocellulose,

tassiu'nr nitrate or ammonium nitrate, ;,be added to the emulsionsupport the latter is" thereby rendered non-electric, and the objectionablc electrical manifestations will be premaking film described inLetters Patent No. 4717,2022, granted December 16,1889, tothe EastmanDry Plate and Film Company, is practiced, said method consisting indepositing or spreading a nitrocellulose compound upon a plate-glasssupport, the emulsion bethe support.

hen making film according to this patent, I prefer to incorporate in thenitrocellunitrate, the proportion of which I have used with successbeing about ten (10) grains to the pound, but it is obvious that alarger or cient quantity to aifeet the quality of the film or thefilmsupport.

In Letters Patent No. 441,881, granted to me December 2, 1890, l havedescribed an improvedfilm consisting of a nitrocellulose support sealedbetween two'gelatin coatings, one of which is the emulsion, said filmbeing made by depositing upon a plate-glass table or support, first, agloating of insoluble gelatin, then a nitrocellulose compound, andfinally the sensitiveemulsion, the whole when making this film also .aconsiderable'aniount isrende'red worthless by the electrical dischargesproduced w en it is stripped from the glass which, however; can beprevented preferably one of the alkali nitrates, as'Zpo-i vented bothduring the manufacture of the film, its subsequent treatment, and whenused in roll-holders. flhese discharges or sparksv are particularyapparent when the method of ing afterward applied or coated upon it andthe whole after. drying being stripped from lose compoundasmall quantityof ammonium smallerlamount could be used if not in sufii stancestherein,being precipitated by them,

drybeing stripped from theglass, and in r by adding to the solution ofgelatin that is tassium nitrate, and I have used with success aboutfifty (50) grains to the pound, but, as before stated, a greater or lessamount such as would not affect thev quality of the film may beemployed.

' As the proportion or the other ingredients.

employed in both the nitrocellulose compounds and the gelatin and theapparatus and manipulations necessary'to manufacture the film have beendescribed in the beforementioued patents and other applications nowpendingat-the Patent Office, it is deemed unnecessary herein tospecifically describe.

the same.

Thefilm produced by my invention, having what I term a non-electricsupport, is found to be practically free from the electrical markingsand can be wound and unwound and used in roll-holders of the usual orany preferred construction in long lengths withoutliability of beingdamaged from these causes, and small sheets or detached pieces ofphotographic film, the supports of which are rendered non-electric,either during the methods of manufacturingj'usfdescribed or whenmanufactured by other methods,'can be used without liability of beingaffected in an objectionable manner] lVhile I have described one methodof manufacturing my improved film and one material that can be usedwith. success, I do not wish to be confined to either of these, as anumber of other substances producing the samc'results can be used andother methods of manufacture employed.

I claim as my invention 1. As an article of manufacture, a photographicfilm consisting of a non electric transparent or translucent supportcontaining a nitrocellulose compound and a superposed coating sensitiveto the action of light, as set forth.

2. As an article of manufacture, a flexible photographic film consistingof a flexible transparent or translucent support composed of anitrocellulose compound containing an inorganic salt solublein'nitrocellulose solvents, as methyl alcohol, and a superposedgelatino-argentic emulsion, as set forth.

3-. As an article of manufacture, afiexible photographic film consistingof a flexible sup.- portcomposed of a nitrocellulose compound containingan alkali nitrate and a superposed gelatino-argent-ic emulsion, as setforth.

4. As an article of manufacture, a flexible photographicfilm consistingof a flexible support composed of a nitrocellulose compound containingammonium nitrate and a superposed gelatino-argentic-emulsion, as setforth.

5. As an article of manufacture, a flexible photographic film consistingof a flexible support composed in'part of a nitrocellulose compound anrendered non-electric and a superposed gelatino-argentic emulsion, asset forth.

6. In the method of. manufaoturingsensitive photographic film involvingthe deposit upon a vitreous support of a fluid substance which when dryforms the support for the sensitive emulsion, and the subsequentstripping of the complete film from the vitreous support, the improved.step consisting in rendering the emulsion support non-electric wherebywhen the film is stripped from said support electrical discharges andthe consequent fogging of the film are prevented, as set forth.

7. The method of manufacturing transparent or translucent sensitivephotographic film consisting in adding to a fluid nitrocellulosecompound, which when. dry forms the support for the sensitive, emulsion,a quantity of an inorganic salt soluble in the solvents ofnitrocellulose, as methyl alcohol, and which will not precipitate any ofthe materials of the compound, nor be precipitated by them, spreadingsaid fluid compound upon a vitreous support, then drying it, thenspreading a sensitive emulsion thereon, and drying it, and finallystripping the complete film from the vitreous support, as setforth.

8. The method of manufacturing sensitive photographic film consisting inadding to a fluid substance, which when dry forms the Support for thesensitive emulsi0n,a quantity of an alkali nitrate soluble in thesolvents of said substance, spreading said fluid substance upon aVitreous support, then drying it, then spreading a sensitive emulsionthereon, and drying it, and finally stripping the complete film from thesupport, as set forth.

0. The method of manufacturing sensitive photographic film consisting inadding to a fluid nitrocellulose compound which when dry forms thesupport for the sensitive emulsion, a quantity of ammonium nitrate. thenspreading said compound upon a vitreous support and drying it, thenspreading a sensitive emulsion thereon and drying it, and finallystripping the complete film from the vitreous support, as set forth.

10.' In the method of manufacturing scnsione, FASTMAN.

Witnesses .llonacn hlCGljlllE, Flilfl CHU'nrn.

